The oligosaccharide α-cyclodextrin has modest effects to slow gastric emptying and modify the glycaemic response to sucrose in healthy older adults

Cyclodextrin as a singular oligosaccharide: Recent advances of health benefit and in food applications

Cyclodextrins (CDs) are cyclic oligosaccharides derived from the enzymatic degradation of starch. Their distinct molecular shape, which resembles a truncated cone with a hydrophobic interior and a hydrophilic outer surface, enables the formation of inclusion complexes via host-guest interactions. These complexes facilitate beneficial modifications such as enhancing the solubility and stabilizing unstable guest molecules. By forming inclusion complexes with bioactive components and drugs, CDs can increase the bioavailability of these compounds, providing benefits in the treatment of various diseases. Particularly, β-CD can form complexes by trapping hydrophobic molecules such as cholesterol in its hydrophobic cavity. Moreover, CDs are considered significant soluble dietary fibers due to their resistance against human digestive enzymes and their utilization by intestinal microbiota. All these features suggest that CDs could encapsulate phospholipids and food components, potentially improving or preventing metabolic diseases such as cardiovascular diseases, diabetes, and neurological disorders by blocking the absorption of carbohydrates, fats, and cholesterol. This review seeks to investigate the clinical effects and mechanisms of action considering all their potential properties and their relevance to health by utilizing in vivo, in vitro, animal, and human studies.

Alpha-cyclodextrin increases glucagon-like peptide-1 secretion in multiple models and improves metabolic status in mice

Alpha-cyclodextrin (α-CD) is a non-absorbable and soluble fiber that causes weight loss. We studied whether this is due to an effect on GLP-1 secretion. In GLUTag cells, α-CD increased GLP-1 secretion up to 170% via adenylyl cyclase, phospholipase C, and L-type calcium channels dependent processes. In rat isolated colon perfusions, luminal α-CD increased GLP-1 secretion with 20%. In lean mice, once daily α-CD versus saline caused weight loss and lowered the peak in glucose after an oral glucose tolerance test (OGTT). In obese mice, α-CD added to high-fat diet caused weight loss similar to the control group (receiving cellulose). However, compared to cellulose, the α-CD group ate less. During an OGTT, no differences were observed in glucose, insulin and GLP-1. Thus, α-CD increases GLP-1 secretion in a dose-dependent manner and could be a safe and easy addition to food products to help reduce body weight.

How Do Cyclodextrins and Dextrans Affect the Gut Microbiome? Review of Prebiotic Activity

The modulation of the gut microbiome through dietary components has garnered significant attention for its potential health benefits. Prebiotics, non-digestible food ingredients that promote the growth of beneficial gut bacteria, play a crucial role in maintaining gut health, enhancing immune function, and potentially preventing various metabolic and inflammatory disorders. This review explores the prebiotic activity of cyclodextrins and dextrans, focusing on their ability to influence gut microbiota composition and function. Both cyclodextrins and dextrans have demonstrated the capacity to promote the growth of beneficial bacterial populations, while also impacting short-chain fatty acid production, crucial for gut health.

Polysaccharide-dextrin thickened fluids for individuals with dysphagia: recent advances in flow behaviors and swallowing assessment methods

The global aging population has brought about a pressing health concern: dysphagia. To effectively address this issue, we must develop specialized diets, such as thickened fluids made with polysaccharide-dextrin (e.g., water, milk, juices, and soups), which are crucial for managing swallowing-related problems like aspiration and choking for people with dysphagia. Understanding the flow behaviors of these thickened fluids is paramount, and it enables us to establish methods for evaluating their suitability for individuals with dysphagia. This review focuses on the shear and extensional flow properties (e.g., viscosity, yield stress, and viscoelasticity) and tribology (e.g., coefficient of friction) of polysaccharide-dextrin-based thickened fluids and highlights how dextrin inclusion influences fluid flow behaviors considering molecular interactions and chain dynamics. The flow behaviors can be integrated into the development of diverse evaluation methods that assess aspects such as flow velocity, risk of aspiration, and remaining fluid volume. In this context, the key in-vivo (e.g., clinical examination and animal model), in-vitro (e.g., the Cambridge Throat), and in-silico (e.g., Hamiltonian moving particles semi-implicit) evaluation methods are summarized. In addition, we explore the potential for establishing realistic assessment methods to evaluate the swallowing performance of thickened fluids, offering promising prospects for the future.

Can the Oral Bioavailability of the Discontinued Prostate Cancer Drug Galeterone Be Improved by Processing Method? KinetiSol® Outperforms Spray Drying in a Head-to-head Comparison

Galeterone, a novel prostate cancer candidate treatment, was discontinued after a Phase III clinical trial due to lack of efficacy. Galeterone is weakly basic and exhibits low solubility in biorelevant media (i.e., ~ 2 µg/mL in fasted simulated intestinal fluid). It was formulated as a 50-50 (w/w) galeterone-hypromellose acetate succinate spray-dried dispersion to increase its bioavailability. Despite this increase, the bioavailability of this formulation may have been insufficient and contributed to its clinical failure. We hypothesized that reformulating galeterone as an amorphous solid dispersion by KinetiSol® compounding could increase its bioavailability. In this study, we examined the effects of composition and manufacturing technology (Kinetisol and spray drying) on the performance of galeterone amorphous solid dispersions. KinetiSol compounding was utilized to create galeterone amorphous solid dispersions containing the complexing agent hydroxypropyl-β-cyclodextrin or hypromellose acetate succinate with lower drug loads that both achieved a ~ 6 × increase in dissolution performance versus the 50-50 spray-dried dispersion. When compared to a spray-dried dispersion with an equivalent drug load, the KinetiSol amorphous solid dispersions formulations exhibited ~ 2 × exposure in an in vivo rat study. Acid-base surface energy analysis showed that the equivalent composition of the KinetiSol amorphous solid dispersion formulation better protected the weakly basic galeterone from premature dissolution in acidic media and thereby reduced precipitation, inhibited recrystallization, and extended the extent of supersaturation during transit into neutral intestinal media.

Reduction of thyroid radioactive iodine exposure by oral administration of cyclic oligosaccharides

Alpha-cyclodextrin, a six D-glucose cyclic oligosaccharide, has several applications in food and pharmaceuticals, but has also been reported to retain iodine in a stable manner for 16 months. Radioactive iodine, which may cause thyroid cancer and hypofunction, must be properly managed. If the absorption of radioactive iodine is suppressed, it can be expected to lead to a reduction in thyroid exposure. This study clarified the inhibition of radioactive iodine absorption by the oral administration of α-cyclodextrin in a murine model using direct measurement of single photon emission computed tomography. The uptake of radioactive iodine into the thyroid gland in mice administered with radioactive iodine and an α-cyclodextrin solution was approximately 40% lower after 24 h. The finding that oral uptake of α-cyclodextrin has an inhibitory effect on the transfer of radioactive iodine to the thyroid gland has potential for application in many fields such as food, pharmaceuticals, nuclear emergency preparedness, and medicine.

The Effect of Alpha-Cyclodextrin on Postprandial Glucose Excursions: a Systematic Meta-Analysis

Alpha-cyclodextrin (αCD) is a bacterial product that is widely used as a food ingredient. In the European Union (EU), αCD is regulated as a dietary fiber with an authorized health claim "for contributing to the reduction of postprandial glycemic responses." In the US, αCD is generally recognized as save (GRAS), but on April 25, 2022, the U.S. Food and Drug Administration (FDA) rejected the inclusion of αCD in the list of dietary fibers because "the strength of the scientific evidence does not support a finding of a beneficial effect of αCD on postprandial blood glucose …" To evaluate the strength of this scientific evidence, this meta-analysis reviews clinical trials conducted to test the effect of αCD on the rise of blood glucose and insulin levels during three hours after consumption of a meal comprising carbohydrates, fats, and proteins. Several issues related to the standardization of the outcomes, the choice of the statistical methods in the cross-over studies conducted, and the choice of methods for the aggregation of P-values are discussed. It is concluded that the administration of αCD not only reduces the postprandial glycemic responses, but the absence of an increase in insulin levels suggests that αCD acts independently of increasing insulin production and, thus, the beneficial effect of αCD is not affected by insulin resistance.

Lecithin Inclusion by α-Cyclodextrin Activates SREBP2 Signaling in the Gut and Ameliorates Postprandial Hyperglycemia

BACKGROUND

α-cyclodextrin (α-CD) is one of the dietary fibers that may have a beneficial effect on cholesterol and/or glucose metabolism, but its efficacy and mode of action remain unclear.

METHODS

In the present study, we examined the anti-hyperglycemic effect of α-CD after oral loading of glucose and liquid meal in mice.

RESULTS

Administration of 2 g/kg α-CD suppressed hyperglycemia after glucose loading, which was associated with increased glucagon-like peptide 1 (GLP-1) secretion and enhanced hepatic glucose sequestration. By contrast, 1 g/kg α-CD similarly suppressed hyperglycemia, but without increasing secretions of GLP-1 and insulin. Furthermore, oral α-CD administration disrupts lipid micelle formation through its inclusion of lecithin in the gut luminal fluid. Importantly, prior inclusion of α-CD with lecithin in vitro nullified the anti-hyperglycemic effect of α-CD in vivo, which was associated with increased intestinal mRNA expressions of SREBP2-target genes (Ldlr, Hmgcr, Pcsk9, and Srebp2).

CONCLUSIONS

α-CD elicits its anti-hyperglycemic effect after glucose loading by inducing lecithin inclusion in the gut lumen and activating SREBP2, which is known to induce cholecystokinin secretion to suppress hepatic glucose production via a gut/brain/liver axis.

Blackcurrant (Ribes nigrum) lowers sugar-induced postprandial glycaemia independently and in a product with fermented quinoa: a randomised crossover trial

Berries rich in anthocyanins have beneficial effects on postprandial glycaemia. We investigated whether blackcurrant (75 g in a portion) independently and in a product with fermented quinoa induced similar effects on the sugar-induced postprandial glucose metabolism as observed before with 150 g of blackcurrant. Twenty-six healthy subjects (twenty-two females and four males) consumed four test products after fasting overnight in a randomised, controlled crossover design. Each test product portion contained 31 g of available carbohydrates and had similar composition of sugar components: 300 ml water with sucrose, glucose and fructose (SW; reference), blackcurrant purée with added sugars (BC), a product consisting of the blackcurrant purée and a product base with fermented quinoa (BCP) and the product base without blackcurrant (PB). Blood samples were collected at 0, 15, 30, 45, 60, 90, 120 and 180 min after eating each test product to analyse the concentrations of glucose, insulin and NEFA. In comparison with the SW, the intake of both the BC and BCP resulted in reduced glucose and insulin concentrations during the first 30 min, a more balanced decline during the first hour and improved glycaemic profile. The BCP induced more efficient effects than the BC due to the product base with fermented quinoa. A rebound of NEFA after the sugar-induced hypoglycaemic response was attenuated at the late postprandial phase by the BC and BCP. In conclusion, we showed that 75 g of blackcurrant and the product with fermented quinoa were able to lower postprandial glycaemia and insulinaemia.

The road ahead for health and lifespan interventions

Aging is a modifiable risk factor for most chronic diseases and an inevitable process in humans. The development of pharmacological interventions aimed at delaying or preventing the onset of chronic conditions and other age-related diseases has been at the forefront of the aging field. Preclinical findings have demonstrated that species, sex and strain confer significant heterogeneity on reaching the desired health- and lifespan-promoting pharmacological responses in model organisms. Translating the safety and efficacy of these interventions to humans and the lack of reliable biomarkers that serve as predictors of health outcomes remain a challenge. Here, we will survey current pharmacological interventions that promote lifespan extension and/or increased healthspan in animals and humans, and review the various anti-aging interventions selected for inclusion in the NIA's Interventions Testing Program as well as the ClinicalTrials.gov database that target aging or age-related diseases in humans.

Alpha-Cyclodextrin Attenuates the Glycemic and Insulinemic Impact of White Bread in Healthy Male Volunteers

The demonstration of a physiological benefit has recently become an indispensible element of the definition of dietary fibers. In the here-reported pilot study, the effect of alpha-cyclodextrin (alpha-CD) on the postprandial glycemic and insulinemic effect of starch was examined. Twelve fasted, healthy male volunteers received, on three subsequent days, a test breakfast consisting of (A) 100 g fresh white bread (providing 50 g starch) and 250 mL drinking water, (B) the same bread with a supplement of 10 g alpha-CD dissolved in the drinking water, and (C) 25 g alpha-CD dissolved in drinking water. Capillary and venous blood was sampled before the breakfast and in regular intervals for a three-hour period thereafter. Glucose was determined in capillary blood and insulin in the plasma of venous blood samples. Breakfast (A) led to a rapid rise in blood glucose and insulin. In breakfast (B), alpha-CD reduced the areas under the curve of blood glucose and insulin significantly by 59% and 57%, respectively, demonstrating that alpha-CD inhibits and thereby delays starch digestion. Treatment (C) was not associated with a rise of blood glucose. Hence, alpha-CD complies with the current definition of dietary fiber in every respect.

Synthesis of novel α-glucans with potential health benefits through controlled glucose release in the human gastrointestinal tract

The glycemic carbohydrates we consume are currently viewed in an unfavorable light in both the consumer and medical research worlds. In significant part, these carbohydrates, mainly starch and sucrose, are looked upon negatively due to their rapid and abrupt glucose delivery to the body which causes a high glycemic response. However, dietary carbohydrates which are digested and release glucose in a slow manner are recognized as providing health benefits. Slow digestion of glycemic carbohydrates can be caused by several factors, including food matrix effect which impedes α-amylase access to substrate, or partial inhibition by plant secondary metabolites such as phenolic compounds. Differences in digestion rate of these carbohydrates may also be due to their specific structures (e.g. variations in degree of branching and/or glycosidic linkages present). In recent years, much has been learned about the synthesis and digestion kinetics of novel α-glucans (i.e. small oligosaccharides or larger polysaccharides based on glucose units linked in different positions by α-bonds). It is the synthesis and digestion of such structures that is the subject of this review.

The Soluble Fiber α-Cyclodextrin Does Not Increase the Fecal Losses of Dietary Fat in Adults-A Double-Blind, Randomized, Placebo-Controlled, Crossover Trial

Background

α-Cyclodextrin (α-CD), a soluble dietary fiber, may improve abnormal plasma lipids and promote weight loss. Preliminary evidence suggests that it may exert these effects by binding dietary fat and reducing absorption; this has not been tested in humans.

Objective

The primary objective was to test whether supplemental α-CD increases fecal content of dietary lipid in humans.

Methods

This was a randomized, double-blind, placebo-controlled, crossover study completed at the Mayo Clinic. Eight healthy volunteers, 5 premenopausal women and 3 men ages 23-54 y with body mass index (BMI; kg/m2) 18-27, underwent 2 separate study visits with a ≥2-wk washout period. The first morning of each visit volunteers consumed a standardized breakfast (14.5% protein, 27.5% fat, 60% carbohydrate, and 1.5 kcal/mL) containing [14C]tripalmitin and [3H]triolein with 2 g of α-CD or placebo, followed by 2 g of α-CD or placebo per meal for 2 more days. Volunteers consumed 100 g/d of dietary fat. Feces were collected for 72 h after the labeled breakfast to measure radiotracer content and total fecal fat. Radiotracer appearance in plasma TGs was measured at intervals after the labeled meal as a secondary outcome.

Results

Virtually no 3H radiotracer, but an average of ∼20% of the 14C radiotracer was recovered in fecal lipids, with no difference between α-CD and placebo. Total fecal fat content and radiotracer appearance in postprandial plasma TGs did not differ between the α-CD and placebo treatments. Plasma appearance of 14C-TG was 37% ± 14% less (P < 0.0001) than 3H-TG.

Conclusions

α-CD supplementation did not increase loss of dietary lipid in stool or total fecal fat compared with placebo in healthy adults. Greater stool loss and lesser appearance in plasma TGs of tripalmitin-derived [14C] compared with triolein-derived [3H] TGs imply different metabolic handling of these 2 dietary fat tracers. This trial was registered at www.clinicaltrials.gov as NCT03002168.

Inhibitory effects of alpha-cyclodextrin and its derivative against sucrose-induced hyperglycemia in an in vivo evaluation system

Cyclodextrins (CyDs) are cyclic oligosaccharides consisting of six to eight glucose residues. Administration of α-CyD (six glucose residues) inhibits sucrose-induced hyperglycemia in humans. Here we show that oral administration of α-CyD and dimethyl α-CyD suppresses sucrose-induced hyperglycemia in an in vivo evaluation system using silkworms. On the other hand, β-CyD (seven glucose residues), γ-CyD (eight glucose residues), and their derivatives did not show the suppressive effect. These findings suggest that dimethyl α-CyD is a new inhibitor against sucrose-induced hyperglycemia and the silkworm system is useful for evaluation of suppressive activities of α-CyD derivatives against postprandial hyperglycemia.

Cyclodextrins in Food Technology and Human Nutrition: Benefits and Limitations

Cyclodextrins are tasteless, odorless, nondigestible, noncaloric, noncariogenic saccharides, which reduce the digestion of carbohydrates and lipids. They have low glycemic index and decrease the glycemic index of the food. They are either non- or only partly digestible by the enzymes of the human gastrointestinal (GI) tract and fermented by the gut microflora. Based on these properties, cyclodextrins are dietary fibers useful for controlling the body weight and blood lipid profile. They are prebiotics, improve the intestinal microflora by selective proliferation of bifidobacteria. These antiobesity and anti-diabetic effects make them bioactive food supplements and nutraceuticals. In this review, these features are evaluated for α-, β- and γ-cyclodextrins, which are the cyclodextrin variants approved by authorities for food applications. The mechanisms behind these effects are reviewed together with the applications as solubilizers, stabilizers of dietary lipids, such as unsaturated fatty acids, phytosterols, vitamins, flavonoids, carotenoids and other nutraceuticals. The recent applications of cyclodextrins for reducing unwanted components, such as trans-fats, allergens, mycotoxins, acrylamides, bitter compounds, as well as in smart active packaging of foods are also overviewed.

Preclinical safety evaluation of low molecular weight galactomannans based standardized fenugreek seeds extract

The objective of the present study was to evaluate acute oral toxicity, subchronic toxicity, and mutagenic potential of low molecular weight galactomannans based standardized fenugreek seeds extract (LMWGAL-TF) in laboratory animals rats as per Organization for Economic Co-operation and Development (OECD) guidelines. For the acute toxicity (AOT) study, LMWGAL-TF was orally administered to Sprague-Dawley (SD) rats at a dose of 2000 mg/kg with vehicle control (VC) group (n = 5 per sex per group) as per OECD guideline no. 423. For the repeated dose toxicity study, the SD rats were orally administered with a daily oral dose of LMWGAL-TF 250, 500 and 1000 mg/kg/day with VC group (n = 15 per sex) for a period of 90 days followed by a recovery period of 28 days as per OECD guideline no. 408. The effects on body weight, food and water consumption, organ weights with hematology, clinical biochemistry, and histology were studied. The mutagenic potential of LMWGAL-TF was tested using reverse mutation assay (AMES test, OECD guideline No. 471). The LMWGAL-TF did not show mortality or treatment-related adverse signs during acute (dose 2000 mg/kg) and subchronic (90-days repeated dose 250, 500 and 1000 mg/kg) administration. The LMWGAL-TF showed oral lethal dose (LD₅₀) more than 2000 mg/kg during AOT study. The dose of 1000 mg/kg was found as no observed adverse effect level (NOAEL) in rats during subchronic toxicity study. Furthermore, LMWGAL-TF did not show mutagenic potential in vitro. In conclusion, LMWGAL-TF was found safe during acute and subchronic (90 days repeated dose) toxicity studies in rats with no mutagenicity.

Honey--a novel antidiabetic agent

Diabetes mellitus remains a burden worldwide in spite of the availability of numerous antidiabetic drugs. Honey is a natural substance produced by bees from nectar. Several evidence-based health benefits have been ascribed to honey in the recent years. In this review article, we highlight findings which demonstrate the beneficial or potential effects of honey in the gastrointestinal tract (GIT), on the gut microbiota, in the liver, in the pancreas and how these effects could improve glycemic control and metabolic derangements. In healthy subjects or patients with impaired glucose tolerance or diabetes mellitus, various studies revealed that honey reduced blood glucose or was more tolerable than most common sugars or sweeteners. Pre-clinical studies provided more convincing evidence in support of honey as a potential antidiabetic agent than clinical studies did. The not-too-impressive clinical data could mainly be attributed to poor study designs or due to the fact that the clinical studies were preliminary. Based on the key constituents of honey, the possible mechanisms of action of antidiabetic effect of honey are proposed. The paper also highlights the potential impacts and future perspectives on the use of honey as an antidiabetic agent. It makes recommendations for further clinical studies on the potential antidiabetic effect of honey. This review provides insight on the potential use of honey, especially as a complementary agent, in the management of diabetes mellitus. Hence, it is very important to have well-designed, randomized controlled clinical trials that investigate the reproducibility (or otherwise) of these experimental data in diabetic human subjects.